1. Field of Invention
This invention relates to catheter devices using guide wires for guiding the catheter to the desired location within a body. More particularly, this invention relates to such catheter devices which include motor driven drive unit for driving a torque cable. Specifically, the invention herein relates to structures which control such a guide wire from migrating along its longitudinal axis while the torque cable is being operated by a motor drive unit.
2. Previous Art:
As described in U.S. Pat. Nos. 5,250,059; 5,084,010 and 4,479,952 which are specifically incorporated herein by reference, there exists a plethora of different catheter designs. In many catheter designs, specifically where directional atherectomy catheters are used, it is desirable to use a guide wire to guide the catheter to the desired position within a body.
In order to guide the catheter to the desired position within the body, the catheter is used in conjunction with a motor drive unit, a torque cable and a guide wire. Typically, the torque cable consists of a cable having a hollow interior wherein one end of the cable is connected to the motor drive unit and the other end of the unit is connected to a work element. Work elements can include cutting devices, ablation elements or even telemetry. The guide wire is located in the central interior opening of the torque cable. The guide wire is made from material such as spring steel or Nitinol. The guide wire typically has a diameter of between 0.009" and 0.0018".
Typically, the guide wire is manipulated to the desired location by rotating and hand feeding the guide wire through the cutter torque cable via a conduit inside the motor drive unit. Unfortunately, when the cutter torque cable is spun by the motor drive unit, the spinning action of the cutter torque cable against the guide wire causes a sympathetic spinning action of the guide wire, which is located in and protrudes from the central lumen in the cutter torque cable. The cutter torque cable can also be translated along the longitudinal axis of cable with or without the rotation of the cutter. This translational movement of the cutter torque cable also causes sympathetic translation of the guide wire which is located in and protrudes from the central lumen of the cutter torque cable. Such migration of the guide wire can cause trauma to the biological conduit near the treatment site. While controlling the axial migration of the guide wire, the guide wire needs to rotate freely as the sympathetic action between the cutter torque cable and guide wire may varyingly dictate. If the guide wire is kept from rotating at the proximal end, the spinning action of the cutter torque cable against the guide wire may cause the distal end of the guide wire to wind up and fail.
What is needed is a device for controlling the migration of the guide wire while allowing the guide wire to spin during rotation and longitudinal motion of the cutter torque cable. The device for controlling the guide wire migration should fit within the conventional motor drive system and should not add greatly to the expense of the operation.